Any conversation about AbbVie has to begin with Humira, the best-selling drug in the world and the drugmaker's most important product. That clock is ticking, however, with company execs not confident that they can stave off competitors past 2020. Given that approaching cliff, AbbVie's moves to wean itself off Humira sales began to take shape this past year. Imbruvica, the lymphoma treatment it acquired for $21 billion in its 2015 buyout of Pharmacyclics, saw impressive sales to start 2017 — growing by nearly 45%, to $551 million in the first three months of the year versus the year-ago period. AbbVie's entrance into the HCV market, however, did not prove as successful: Viekira Pak sales dropped by 58% in the beginning of 2017 to $342 million, which AbbVie execs blamed on market share loss and price erosion due to competition — and the company expects that trend to continue. Experimental drug ABT-494, the company's JAK-inhibitor for rheumatoid arthritis, will also be critical to longer-term success. Scott Brun, VP of AbbVie Ventures, said the company believes that ABT-494 could be a first-in-class drug in RA — which would be a huge boon for AbbVie, especially as competition for Imbruvica nears. AstraZeneca's competitor, acalabrutinib, is already in Phase III trials.